In one example conventional SRAM device, a pull up and a pull down device are formed adjacent each other and in electrical contact to create an inverter device. The pull down device may be an N-type transistor, and the pull up device may be a P-type transistor, where gates of the two transistors are electrically coupled. Further, the SRAM device has multiple inverters laid out in multiple parallel trenches.
In one conventional method, there is PFET metal deposited in N/PFET poly trench. After metal gate photo patterning, the NFET trench is exposed and PFET metal is removed. However, such conventional techniques may leave PFET metal residue, especially in narrow trenches. Metal mixing by NFET and PFET work function metals may make it more difficult to control work function and voltage threshold in the NFET device. Furthermore, such conventional method may fabricate a NFET metal gate using two layers of metals (a PFET work function metal underneath an NFET work function metal). However, the double metal layer makes the opening in trench quite narrow, thereby decreasing the process window for the metal fill and reducing the chance to scale a barrier metal. Accordingly, while some processes may be satisfactory for some applications, improvement would be desired.